Onset of Labor


Researches are continuing to analyze what factors are actually responsible for causing labor to begin. While the exact cause and mechanisms are not known, most evidence points to hormonal changes. Current research suggests that a complicated process that starts in the baby’s brain causes labor to begin. The baby’s hypothalamus, located in his brain, sends a hormone to his pituitary that causes the adrenal glands to increase their production of a chemical that the placenta turns into estrogen. This estrogen then causes the placenta to produce hormones called prostaglandins that cause contractions of the uterus. Thus, the process of chemical reactions that begins with the baby results in the uterine contractions of labor.